Creatine is a naturally occurring amino acid that is derived from the amino acids; glycine, arginine and methionine. Although it is ingested from meats and fish, the human body also synthesizes its own creatine. About 65% of creatine is stored in the musculature of mammals in the form of phosphocreatine (creatine bound to a phosphate molecule), and utilized mostly as a source of energy for muscle. Oral supplementation of creatine has been shown to increase creatine concentration in muscle, and also enables an increase in the resynthesis of phosphocreatine, resulting in a rapid replenishment of ATP within the first two minutes of the start of exercise.
The beneficial effects of creatine supplementation with regard to skeletal muscle are apparently not restricted to the role of creatine in energy metabolism. Creatine supplementation in combination with strength training results in specific, measurable physiological changes in skeletal muscle compared to strength training alone. For example, creatine supplementation amplifies the strength training-induced increase of human skeletal satellite cells as well as the number of myonuclei in human skeletal muscle fibers. Satellite cells, stem cells of adult muscle, are normally in a quiescent state and become activated to fulfill roles of routine maintenance, repair and hypertrophy. Postnatal muscle growth involves both myofiber hypertrophy and increased numbers of myonuclei—the source of which are satellite cells.
Imino sugars constitute a major class of naturally occurring molecules that have important and diverse biological functions. Imino sugars may be pentose, hexose or heptose sugars where at least one oxygen-containing group is replaced by a nitrogen-containing group. These imino sugars are useful in pharmacology, since they have been found to play major roles in the selective inhibition of various enzymatic functions.